I'll explain this one to my wife: I need to spend $6K on an axle so I can save some money on wheels!
I also agree that using an adapter shouldn't be done unless there's a reason other than saving a few dollars to put the wrong wheels on. I didn't plan well with my build: I have a TJ width currie 44 on the front. I was running 35's at the time, and didn't plan on 37's.
A few years later, decided to move to 37's. So bought a Currie 60 for the rear with JK bolt pattern since there are very few 17" wheels that will fit a TJ. So ended up using TJ to JK wheel adapters on the front only.
You will find very few (none?) 17" wheels that will fit a TJ. So if you want to move to a 17" wheel, you will likely have to use the TJ to JK adapters.
Though it is tempting since there are plenty of JK/JL take offs. A few years ago I got nearly brand new JL wheels with street tires that someone was giving away. She just wanted them gone quickly. You can often find take offs with brand new tires for around $400 - $500.
Though I'll note that I did have a tire shop break one of my adapters trying to get it off. Of course, they wouldn't pay for a new adapter, so I had to find some in a hurry. Probably less of a problem if you're doing your own work or have a tire shop that actually knows what they're doing.